Entropy-Motivated Solvation Design for Low-Temperature Ether-Based Electrolyte of Sodium-Ion Batteries

Ether-based electrolytes have attracted increasing attention for the development of low-temperature sodium-ion batteries (SIBs); however, relevant performances are significantly constrained by temperature factors for lack of appropriate modification strategies. Herein, advanced design principles are proposed by integrating an entropy-motivated mechanism to customize the sodium-based solvation configuration at meso- and microscopic scales. Specifically, the tailored ionic clusters along with an increase in disorder guarantee sufficient conductivity at LTs, and the multiple solvation microstructures with weakened ion–solvent interactions concurrently facilitate the desolvation behavior at interfaces. With the assistance of accelerated ion transport kinetics and complementary organic–inorganic interphases featuring an equilibrium of thickness and robustness, Na 3 V 2 (PO 4 ) 2 O 2 F and Na 3 V 2 (PO 4 ) 3 exhibit workability as the temperature approached −80 °C. Moreover, the assembled full cells verify the feasibility at LTs. In short, the rational design strategy with an entropy-dependent effect is introduced to provide an emerging perspective on functional ether-based electrolytes for low-temperature and high-voltage SIBs.